Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque

H, W = map(int,input().split())
S = []
wall = 0
for i in range(H):
    s = list(input())
    wall += s.count("#")
    S.append(s)
q = deque()
q.append([0, 0, 0])
S[0][0] = "#"
while q:
    y, x, cnt = q.popleft()
    if y == H-1 and x == W-1:
        break
    for dy, dx in [[1, 0], [-1, 0], [0, 1], [0, -1]]:
        if 0 <= y + dy < H and 0 <= x + dx < W and S[y + dy][x + dx] == ".":
            q.append([y + dy, x + dx, cnt + 1])
            S[y + dy][x + dx] = "#"

if S[H-1][W-1] == ".":
    print(-1)
else:
    score = H * W - (cnt + 1) - wall
    print(score)